Materials needed for Steel Production in Basic Oxygen Furnace The following types of materials are needed for the production of liquid steel in the basic oxygen furnace (BOF) steelmaking process (Fig 1). Basic raw materials such as hot metal, scrap, and lime etc. Secondary raw materials such as deoxidizers and carburizers. Utility gases such as oxygen, nitrogen, and argon etc. Refractories and Refractory materials such as lining material, gunning material and patching materials etc. Consumable probes such as temperature probes and sampling probes etc. Cooling water for cooling of oxygen blowing lance and exhaust gases. Fig 1 Materials needed for the production of steel in basic oxygen furnace Basic raw Materials The basic raw materials needed for making steel in the BOF converter include (i) hot metal from the blast furnace, (ii) steel scrap and/or any other metallic iron source, (iii) iron ore, and (iv) fluxes. Scrap, charged from a scrap box, is the first material to be charged into the BOF. The hot metal is then poured into the converter from a hot metal charging ladle, after which the blowing with oxygen gas is started. The fluxes, usually in lump form, are charged into the BOF through a bin system after the start of the oxygen blow. The fluxes can also be injected into the furnace in powder form through bottom tuyeres. The composition and amounts of basic raw materials used in the BOF converter vary from one steel melting shop to another, depending on their availability and the economics of the process. The hot metal or liquid iron is the primary source of iron units and energy. Hot metal is received from the blast furnaces in either open top or torpedo cars. In case of open top ladles, hot metal is poured...

Argon gas and its usage in Steel Plant Argon (Ar) gas is present in very small percentage in the atmosphere. Argon is very inert and hence it is referred to as one of the noble gases. It is not known to form true chemical compounds. It makes a good atmosphere for working with air sensitive materials since it is heavier than air and less reactive than nitrogen gas. Argon gas is the most abundant of the noble gases. It is a non-reactive component of the atmosphere. It constitutes 0.934 % by volume and 1.288 % by mass of the earth’s atmosphere. Argon was suspected to be present in air by Henry Cavendish in 1785 but was not isolated until 1894 by Lord Rayleigh and Sir Willam Ramsay at University college London in an experiment in which they removed all of the oxygen, carbon dioxide, water and nitrogen from a sample of clean air. Argon gas is produced by the fractional distillation of liquid air at the cryogenic air separation plants. It is produced, most commonly, in conjunction with the manufacture of high purity oxygen using cryogenic distillation of air. Since the boiling point of argon is very close to that of oxygen (a difference of only 2.9 deg C) separating pure argon from oxygen (while also achieving high recovery of both products) requires many stages of distillation. For many decades, the most common argon recovery and purification process used several steps namely (i) taking of a side-draw stream from the primary air separation distillation system at a point in the low-pressure column where the concentration of argon is highest, (ii) processing the feed in a crude argon column which returns the nitrogen to the low pressure column and produces a crude argon product, (iii) warming the crude argon and reacting...

Nitrogen gas and its usage in Steel Plant Nitrogen is a non-reactive component of the atmosphere which is not life supporting. The percentage of nitrogen in air is 78.06 % by volume or 77 % by weight of the air. The composition of air is shown in Fig 1. Fig 1 Composition of air The element nitrogen was discovered as a separable component of air, by Scottish physician Daniel Rutherford, in 1772. Nitrogen was also studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air. Nitrogen is produced in large quantities and at high purity as a gas or liquid through the liquefaction and distillation of ambient air at the cryogenic air separation plants. It is also produced on commercial scales as a lower purity gas by adsorption technologies (pressure swing adsorption, PSA), or diffusion separation processes (permeation through specially designed hollow fibers). Gaseous nitrogen is called in short as GAN while the liquid nitrogen is called in short as LIN. Liquid nitrogen is a cryogenic liquid. Cryogenic liquids are liquefied gases that have a normal boiling point below – 150 deg C. Liquid nitrogen has a boiling point of -195.8 deg C. Because the temperature difference between the product and the surrounding environment is substantial, it is necessary to keep the liquid nitrogen insulated from the surrounding heat. Nitrogen is often stored as a liquid, although it is used primarily as a gas. Liquid storage is less bulky and less costly than the equivalent capacity of high-pressure gaseous storage. A typical storage system consists of a cryogenic storage tank, one or more vaporizers and a pressure control system. The cryogenic tank is constructed, in principle, like a vacuum flask. There is an inner vessel...

CLU process for Stainless Steel Production Stainless steel production process has some basic features such as carbon (C) removal, deoxidation and desulphurization. In the production process, these operations are generally combined with some alloying with solid material as well as nitrogen (N2) control. These requirements are met in different ways in various processes being deployed for the production of stainless steel. The CLU process is similar to the AOD (argon oxygen decarburization) process for making stainless steels. CLU refers to the Creusot-Loire Uddeholm process for stainless steel production. It also uses liquid steel from an electric arc furnace (EAF) or any other similar primary steel making furnace. The major impetus for the development of the CLU process was the idea to use superheated steam as the diluting gas instead of argon (Ar) gas which is used in the AOD process. Superheated steam has been used as a process gas in stainless steel production since the early 1970s when this technology was developed at Uddeholms Degerfors steel plant in Sweden. In France a similar development took place within the Creusot-Loire group. The developed process was named Creusot Loire Uddeholm (CLU) process. The converter originally used in CLU process was a bottom blown converter thus differentiating it from the side blown AOD converter. However, presently CLU process with the use of a side blown converter is also available. The first commercial plant using the CLU process was built in 1973 by Uddeholm. Between 1973 and 2003 stainless steel was produced in Uddeholms Degerfors steel plant in an 80 ton converter where superheated steam, Ar, N2, oxygen (O2) and compressed air were used as process gases. The converter in the Degerfors steel plant was operated for 30 years as a CLU process for stainless steel production before...

Stainless Steel Manufacturing Processes Stainless steels contain from 10 % to 30 % chromium. These steels also contain varying amounts of nickel, molybdenum, copper, sulphur, titanium, and niobium etc. The majority of production of stainless steel was through the electric arc furnace (EAF) till around 1970. With the use of tonnage oxygen in steel production, the EAF stainless steel making practice changed. Oxygen gas could be used for improving the decarburization rate. This could be achieved by injecting high oxygen potential but it was accompanied by the adverse reaction of extensive oxidation of chromium to the slag. This necessitated a well defined reduction period in which ferro silicon was used to reduce the oxidized chromium from the slag. Production of stainless steel started by duplex process with the successful development of argon oxygen decarburization (AOD) converter process. Though duplex process with AOD converter is the prominent one, there are several duplex processes are being used today for making stainless steels. In these processes there is an EAF or similar furnace that melts down scrap, ferroalloys and other raw materials to produce the liquid steel. This liquid steel, which contains most of chromium and nickel as well as some other alloying elements, is the charge of the converters. The converters are used to achieve low carbon stainless steels. The versatility of the EAF-AOD duplex process led steelmakers to re-examine the use of different converters for melting of stainless steels. This led to the development of several other converters for duplex processes. The development work to make stainless steels using conventional BOF (basic oxygen furnace) had begun in the late 1950s and early 1960s. By the mid 1960s, some steelmakers were using existing BOF converters for a partial decarburization followed by decarburization in a ladle under...